LS1Formulation

iTrader: (13)

I bought my cam and now I am just waiting for it to arrive, so I need to decide on what heads to buy. It's a Comp 223/227 @ .050 .637/.639 lift on a 111+0 LSA. I plan on installing it two degrees advanced and I don't want to flycut my pistons. I have read a lot on here that if you use 5.3 heads you have to flycut, but I am not sure I will have to given the short duration of my cam. I'm looking at either Patriot LS6 castings with their extreme springs ($1120) or PRC 5.3 Stage 2.5's with 2.02/1.57 valves. ($1199) Seeing as the 2.02 valve only adds .01 out from the centerline of the valve compared to the stock 2.00 size, I can't imagine it would cause much of a PTV clearance issue. Here's the other problem - If I get the LS6 heads, I will have to mill them down to the same 61cc chamber size as the 5.3 heads, which will tighten my PTV clearance as well. Are the valves for both castings sunk in the same amount stock? Or do the 5.3's have longer valves in order to produce a more compact chamber? If they're the same stock, then I definitely would go with the 5.3's since I wouldn't have to mill them, I just have no idea how they're set up. Any info would be much appreciated.

FIVE-O

A) No, I dont think you will have a PTV issue, and B) (not to sound like an ***, but) The best prople to tell you how either head is set up would be to call Patriot/TSP.
But, the 5.3's get my vote.

LS1Formulation

iTrader: (13)

I've called and talked to both, I kind of would like people who've had real world experience with them to tell me what they think.

BOWTIE

You should not have any p/v problems with either choice. Not sure what the CC is for the Patriots, but the 5.3's are more like 63 cc's. I was talking with Jason at TSP last week and am planning on going with a set of these as well but am going to mill them just a bit and I am planning on a 228/234 .642/.598 110 +2 cam so you should be able to do the same.

JRracing

iTrader: (35)

Can't go wrong with either.

PREDATOR-Z

My 5.3s were 63 cc (TSP 2.5s). The difference between 243s and 5.3s is 1cc at best.
The 2.02 might flow 5 cfm better than stock valves at best. I still say get the 243s, 227cc

Xtnct00WS6

iTrader: (8)

I agree. I've had great results with my 243's from Patriot! Give'm a try...you'll put up some great numbers with them. Best bang for the buck out there in my opinion.

LS1Formulation

iTrader: (13)

I thought I would add, I don't plan on spinning this engine much higher than 6300 RPM because of the iffy stock rod bolts. The 5.3's are 220CC and the 243's are 227CC. Seeing as they flow similar numbers, I would assume that the 5.3's would have a higher port velocity which would boost my low end a bit more.

PREDATOR-Z

It is not the runner size you should look at but the cross section

YellowToy/A

iTrader: (1)

Lets see if I can be more help than yesterday. I have heard that the TSP/PRc heads flow as advertise. I would go with the 5.3 and no milling. I would also use .040 cometic gaskets and arp head studs.

I think your P/V will be close with +2. Make sure you check it. I am goint to get the PRC 200cc Terminators for more torque down low.

Make sure the installed hight on the valve springs is correct. That is more lift than I wanted to run. It is very bad mr valve meets mr piston.

shudog

iTrader: (3)

Dude, I got a thread started about this exact same topic also.... can't get a good answer. The cost between the two is negligible as is the stock compression ratio (63cc or 64cc).

LS1Formulation

iTrader: (13)

I think I am going to go with PRC's because Patriots are $1120 with their gold extreme springs and use stock valves, while the PRC's have stainless valves and a slightly smaller combustion chamber and are $1199. Might not be much of a difference, but I need all the help I can get for what I am spending.